A switching power converter is often used when an RF communications system needing a regulated power supply is powered from an unregulated DC source of power, such as a battery, or a regulated DC source of power at a different voltage. The switching power converter is driven from at least one switching signal having a switching frequency. Circuitry within the switching power converter tends to transition synchronously with the switching signal, which may generate voltage spikes, current spikes, or both. The voltage and current spikes may generate interfering noise signals at the fundamental frequency and harmonics of the switching signal. If a frequency of an interfering noise signal falls within the passband of a received RF signal, receiver sensitivity can be degraded, which is known as receiver de-sensitization. The switching signal may have an active state and an inactive state.
The basic operation of a single-phase switching power converter includes receiving a DC input signal into an energy transfer circuit that may transfer energy from the DC input signal into at least one energy transfer element during the active state, and may include transferring energy from the energy transfer element to an energy storage circuit during the inactive state. The single-phase switching power converter provides a regulated DC output signal by transferring energy from the energy storage circuit to the DC output signal during the active state, and by transferring energy from the energy transfer element to the DC output signal during the inactive state. The switching behavior causes ripple currents and voltages at the fundamental frequency and harmonics of the switching signal. Architectures that may reduce ripple currents and voltages include switching power converters with at least two phases.
The basic architecture of a two-phase switching power converter may include two energy transfer circuits instead of one energy transfer circuit. Each energy transfer circuit may have its own switching signal. The two switching signals may share a common frequency, and may be phase-shifted 180 degrees from each other. The two-phase switching power converter may reduce the magnitude of ripple voltages, ripple currents, voltage spikes, current spikes, or any combination thereof; however, the fundamental frequency of the ripple and spikes may be twice the frequency of the switching signal instead of one times the frequency of the switching signal. A higher fundamental frequency of ripple and spikes may increase the magnitude of resulting noise signals that fall within the passband of a received RF signal. Thus, there is a need for a multiple-phase switching power converter having reduced switching noise signals that fall within the passband of a received RF signal.